Vitamin B6, Methionine Linked to Lower Lung Cancer Risk

Scientists have found a link between lower lung cancer risk and higher levels of vitamin B6 and methionine in the bloodstream in a study of current and former smokers. Methionine, an amino acid found in protein, and vitamin B6 may prevent DNA damage and gene mutations, leading researchers to suspect boosting levels of B vitamins and metabolites lowers the chances of getting lung cancer, even for smokers.

Vitamin B deficiency is common in Western populations. The authors say, "Given their involvement in maintaining DNA integrity and gene ex­pression, these nutrients have a potentially important role in inhibiting cancer devel­opment, and offer the possibility of modi­fying cancer risk through dietary changes."

Scientists studied 400,000 individuals to find the link between higher levels of vitamin B6, methionine, and reduced risk of lung cancer. The findings were based on blood samples obtained from participants of the European Prospective Inves­tigation into Cancer and Nutrition (EPIC) cohort study.

After adjusting for other variables, the researchers discovered that study participants with higher levels of vitamin B6 and methionine had a lower risk of developing lung cancer.

According to the authors, "Similar and consistent decreases in risk were observed in never, former, and current smokers, indicating that results were not due to confounding [factors that can influence outcomes] by smoking. The magnitude of risk was also constant with increasing length of follow-up, indicating that the associations were not explained by preclinical disease."

A higher level of vitamin B6 and methionine in the bloodstream was associated with a 50 percent reduced risk of lung cancer. Folate, found in green vegetables, and also a member of the vitamin B family, combined with vitamin B6 and methionine levels that were above average, was associated with a two-thirds reduction in lung cancer risk.

Because lung cancer occurs in former smokers, the scientists say finding ways to prevent the disease are important. The study doesn't prove that higher levels vitamin B6, methionine and folate were responsible for the lower risk of lung cancer found in the analysis, but the association was apparent. The authors say if there is a definite connection between higher levels of vitamin B6, methionine and lower risk of lung cancer; it would become important to establish optimum levels needed for prevention of the disease.

JAMA. 2010;303[23]:2377-2385